3

As far as I know, DDNS, or Dynamic DNS is used to assign a domain name to a device with a non-permanent IP address. Either this device, or the router that it's connected to, has to have a public IP. But is it possible to assign a DDNS domain name to a device that is behind multiple levels of private networks?

traceroute 8.8.8.8 shows this kind of result:

  1. 192.168.1.2 (My device)

  2. 192.168.1.1 (My router)

  3. 10.0.0.1 (My ISP's router)

  4. 10.1.0.1 (Another router with no public IP)

  5. 123.x.x.x (The closest device to me that has a public IP; this is the address that is shown on sites like whatismyipaddress.com)

  6. x.x.x.x (More routers)

  7. 8.8.8.8 (Finally, IP that I tracerouteed.)

My understanding is that, after I install a Dynamic DNS client on my end-device (like No-IP client), it will have a publicly accessible URL like xyz.no-ip.com. But I don't understand how that will work, even if it will work. I think the URL xyz.no-ip.com will resolve into the IP that is shown as my public IP (123.x.x.x; number 4 on above list), and my computer won't be accessible from the public internet anyway.

I just want to understand how it will work before I sign up for a Dynamic DNS service. Please enlighten me.

Improve this question
2
  • DDNS will only let you resolve a domain name to your public IP. It doesn't sound like that's what you want.
    – Sam Forbis
    Commented May 10, 2020 at 4:32
  • 2
    You might be behind multiple levels of NAT, however, just because traceroute reports private IP addresses does not mean you're behind multiple levels of NAT – it's actually quite normal for routes within a single network (ISP) to use private IP addresses as nexthops for 'public' destinations and it doesn't imply NAT in any way. The only useful way to determine whether you're behind multiple NATs is to look at your router's "WAN" IP address (and compare it with what websites report as being your IP address).
    – grawity_u1686
    Commented May 10, 2020 at 9:22

1 Answer 1

Reset to default
5

But is it possible to assign a DDNS domain name to a device that is behind multiple levels of private networks?

You never assign a domain name to the device that is behind several layers of NAT. As you wrote, you assign it to the "device" (router) that has the public IP. Then you can configure this router (and all of those behind it) to do port forwarding to reach the "end-device".

And yes, you can also do that to routers you don't own, like the router of your ISP with the public address.

However, since you don't control those routers, there's no way to port forward from there to the "end-device".

So the question you are probably asking is

If my ISP doesn't give me a public IP, can I use DDNS to work around that?

And the answer to that is "no". You need to pay your ISP to give you a public IP. Or you need to pay someone else to give you a public IP (via a VPN etc.).

Improve this answer
1
  • 2
    Can you please link some of " someone else to give you a public IP"? I'd really appreciate it :)
    – Roberto Manfreda
    Commented Jul 27, 2021 at 17:29

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .